RECYCLING OF A GLYCOSYLPHOSPHATIDYLINOSITOL-ANCHORED HEPARAN-SULFATE PROTEOGLYCAN (GLYPICAN) IN SKIN FIBROBLASTS
RECYCLING OF A GLYCOSYLPHOSPHATIDYLINOSITOL-ANCHORED HEPARAN-SULFATE PROTEOGLYCAN (GLYPICAN) IN SKIN FIBROBLASTS
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DOI：
10.1093/glycob/5.4.407
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发表时间：
1995-06-01
期刊：
影响因子：
4.3
通讯作者：
SCHMIDTCHEN, A
中科院分区：
文献类型：
--
作者：
FRANSSON, L;EDGREN, G;SCHMIDTCHEN, A
We have used suramin and brefeldin A to investigate the nature of a heparan sulphate proteoglycan that appears to recycle from the cell surface to intracellular compartments which synthesize new heparan sulphate chains, Suramin, which would block internalization and deglycanation of a putative recycling cell surface proteoglycan, markedly increases the yield of a membrane-bound proteoglycan with a core protein of 60-70 kDa and unusually long heparan sulphate side chains, When transport of newly made core proteins to their Golgi sites for glycosaminoglycan assembly is blocked, by using brefeldin A, [H-3]glucosamine and [S-35]sulphate incorporation into cell surface-bound heparan sulphate proteoglycan can still take place, After chemical biotinylation of cell surface proteins in brefeldin A-treated cells, followed by metabolic [S-35]sulphation in the presence of the same drug, biotin-tagged [S-35]proteoglycan can be demonstrated, indicating the presence of recycling proteoglycan species, By pre-labelling cells with [H-3]leucine or [H-3]inositol in the presence of suramin, followed by chase labelling with [S-35]sulphate in the presence of brefeldin A, a H-3- and S-35-labelled, hydrophobic heparan sulphate proteoglycan with a core protein of 60-65 kDa is obtained, The proteoglycan loses its hydrophobicity when glucosamine-inositol bonds are cleaved, indicating that it is membrane bound via a glycosylphosphatidylinositol anchor. However, treatment with phosphatidylinositol-specific phospholipase C has no effect, suggesting that the inositol moiety may be acylated, We propose that a portion of the lipid-anchored proteoglycan glypican is internalized, recycled via the Golgi, where heparan sulphate chains are added, and finally re-deposited at the cell surface.
